Enhancing lignin biosynthesis in transgenic plants

Abstract

The present invention provides methods of enhancing lignin biosynthesis in plants. The invention provides, for example, a method of enhancing lignification in a vascular plant by ectopically expressing a nucleic acid molecule encoding an AGL1-like gene product, or an AGL1-like gene product and an AGL5-like gene product in the plant.

We claim:  
     
       1. A method of enhancing lignification in a vascular plant, comprising introducing into the vascular plant an exogenous nucleic acid encoding an AGL1-like gene product comprising a MADS box, an I domain at least 95% identical to the I domain of SEQ ID NO:4, a K domain at least 92% identical to the K domain of SEQ ID NO:4 and a C domain at least 72% identical to the C domain of SEQ ID NO:4, whereby lignification is enhanced due to ectopic expression of said nucleic acid molecule. 
     
     
       2. The method of  claim 1 , further comprising introducing an exogenous nucleic acid encoding an AGL5-like gene product comprising a MADS box, an I domain at least 95% identical to the I domain of SEQ ID NO:6, a K domain at least 92% identical to the K domain of SEQ ID NO:6 and a C domain at least 72% identical to the C domain of SEQ ID NO:6. 
     
     
       3. The method of  claim 1 , wherein said AGL1-like gene product comprises has the amino acid sequence of Arabidopsis AGL1 (SEQ ID NO:4). 
     
     
       4. The method of  claim 2 , wherein said AGL5-like gene product comprises the amino acid sequence of Arabidopsis AGL5 (SEQ ID NO: 6). 
     
     
       5. The method of  claim 1 , wherein said vascular plant is a woody plant. 
     
     
       6. The method of  claim 1 , wherein said exogenous nucleic acid molecule encoding an AGL1-like gene product is operatively linked to an exogenous regulatory element. 
     
     
       7. The method of  claim 6 , wherein said exogenous regulatory element is a constitutive regulatory element. 
     
     
       8. The method of  claim 6 , wherein said exogenous regulatory element is a tissue-selective regulatory element. 
     
     
       9. The method of  claim 8 , wherein said tissue-selective regulatory element is a lignified tissue-selective regulatory element selected from the group consisting of a fiber-selective regulatory element, xylem-selective regulatory element and a tracheid selective regulatory element. 
     
     
       10. A transgenic vascular plant characterized by enhanced lignification, comprising an ectopically expressed nucleic acid molecule comprising a tissue-selective regulatory element operatively linked to an exogenous nucleic acid encoding an AGL1-like gene product comprising a MADS box, an I domain at least 95% identical to the I domain of SEQ ID NO:4, a K domain at least 92% identical to the K domain of SEQ ID NO:4 and a C domain at least 72% identical to the C domain of SEQ ID NO:4. 
     
     
       11. The transgenic vascular plant of  claim 10 , further comprising introducing an exogenous nucleic acid encoding an AGL5-like gene product comprising a MADS box, an I domain at least 95% identical to the I domain of SEQ ID NO:6, a K domain at least 92% identical to the K domain of SEQ ID NO:6 and a C domain at least 72% identical to the C domain of SEQ ID NO:6. 
     
     
       12. The transgenic vascular plant of  claim 10 , wherein said AGL1-like gene product comprises the amino acid sequence of Arabidopsis AGL1 (SEQ ID NO:4). 
     
     
       13. The transgenic vascular plant of  claim 11 , wherein said AGL5-like gene product comprises the amino acid sequence of Arabidopsis AGL5 (SEQ ID NO: 6). 
     
     
       14. The transgenic vascular plant of  claim 10 , wherein said tissue-selective regulatory element is selected from the group consisting of a fiber-selective regulatory element, xylem-selective regulatory element and a tracheid selective regulatory element. 
     
     
       15. A tissue derived from the transgenic vascular plant of  claim 12 , said transgenic vascular plant comprising an ectopically expressed nucleic acid molecule comprising a tissue-selective regulatory element operatively linked to a nucleic acid molecule encoding an AGL1-like gene product. 
     
     
       16. The method of  claim 2 , wherein said exogenous nucleic acid molecule encoding an AGL1-like gene product is operatively linked to an exogenous regulatory element. 
     
     
       17. The method of  claim 16 , wherein said exogenous regulatory element is a constitutive regulatory element. 
     
     
       18. The method of  claim 16 , wherein said exogenous regulatory element is a tissue-selective regulatory element. 
     
     
       19. The method of  claim 18 , wherein said tissue-selective regulatory element is a lignified tissue-selective regulatory element selected from the group consisting of a fiber-selective regulatory element, xylem-selective regulatory element and a tracheid selective regulatory element. 
     
     
       20. The transgenic vascular plant of  claim 11 , wherein the exogenous nucleic acid encoding an AGL5-like product is operatively linked to a tissue-selective regulatory element. 
     
     
       21. The method of  claim 1 , wherein the AGL1-like gene product is ectopically expressed in the valve mesophyll and the valve mesophyll displays enhanced lignification compared to a plant in which the AGL1-like gene product is not ectopically expressed. 
     
     
       22. The transgenic vascular plant of  claim 11 , wherein the AGL1-like gene product is ectopically expressed in the valve mesophyll and the valve mesophyll displays enhanced lignification compared to a plant in which the AGL1-like gene product is not ectopically expressed.